Whitefin weakfish, Cynoscion albus (Photo: Ecosistemas de Costa Rica)
Whitefin weakfish in captivity managed to be bred
Thursday, September 26, 2013, 23:40 (GMT + 9)
Scientists at the Marine Biological Station Juan Bertoglia Richards, of the School of Biological Sciences at the National University (UNA), are investigating the possibility of raising whitefin weakfish (Cynoscion albus) in captivity, a resource having great commercial importance.
This white fleshed fish with a high percentage of proteins is caught in the Gulf of Nicoya, but in recent years its catches decreased so that the researchers intend to obtain specimens in captivity.
After keeping wild whitefin weakfish reproducers in captivity for more than two years, on 20 June scientists from the Culture and Breeding Laboratory of Marine Fish performed the hormonal induction of these specimens.
According to Jorge Boza Abarca, Laboratory coordinator, after waiting a latency period of about 48 hours, "both females and males released their sexual products into the water, hence achieving fertilization and for the first time obtaining fertilized eggs of the whitefin weakfish in captivity."
Boza Abarca explained that wild broodstock specimens are hard to obtain because they are caught by artisan fishermen and are exposed to great stress due to the hours during which they remain hooked on hooks before being transported to the breeding tanks.
Marvin Ramirez, one of the researchers involved in the project, explained that for more than 24 months they took care of eight reproducers - females and males - a task which, he said, demanded a great effort.
To Boza Abarca, achieving the reproduction of whitefin weakfish specimens in captivity is the first step in the development of mariculture in the Gulf of Nicoya, UNA reported.
"From the fertilization phase, what we want to study is the life cycle of the species, to see how much it grows in a year and what size it will reach when mature," Ramirez added.
The researchers plan to install a cage in the fishing area in Chira Island to assess the growth of the fish in order to devise a mariculture project, the newspaper La Nacion reported.
Scientists explain that as a result of the fishing pressure, the sizes to spawn changed from 70 cm to 50 cm, and "as they were smaller fish, the eggs have lower quality," the biologist noted.
The project's backers think about the possibility of releasing fish in the Gulf to help recovery. They also consider the possibility of marking them with microchips to track them.
By Analia Murias